Chylomicrons, VLDL and LDL1 will be isolated from normal control and hyperlipoproteinemic subjects. Each density fraction will be characterized and utilized for substrate specificity studies for lipoprotein lipases, LPL C-1' and LPL C-II. LDL2 will be isolated from normal controls and hyperlipoproteinemic subjects. The major protein moiety of LDL2, ApoB, will be solubilized and separated into its constitutive polypeptides. Each polypeptide will be characterized by chemical and physical-chemical methods.